1. State Key Laboratory of Optoelectronic Materials and Technologies, Guangdong Province Key Laboratory of Display Material and Technology, School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510275, China
2. School of Physics, Sun Yat-sen University, Guangzhou 510275, China
3. School of Materials Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China